U.S. patent number 6,864,891 [Application Number 10/062,803] was granted by the patent office on 2005-03-08 for switching between internal and external display adapters in a portable computer system.
This patent grant is currently assigned to Hewlett-Packard Development Company L.P.. Invention is credited to Robert L. Myers.
United States Patent |
6,864,891 |
Myers |
March 8, 2005 |
Switching between internal and external display adapters in a
portable computer system
Abstract
Systems and methods of switching between internal and external
display adapters in a portable computer system are described. In
one aspect, a graphics controller is configured to convert video
output signals that are received from a processing unit into
locally-generated video control signals and to selectively transmit
to a local video display the video control signals that are
generated locally or video control signals that are received from a
docking station interface. In this way, when undocked, a portable
computer unit may drive the local video display with a local
adapter that is optimized for mobile usage (e.g., enhanced power
management) and, when docked, the portable computer unit may drive
the local video display with a higher performance external display
adapter, which typically is not constrained by power management
considerations.
Inventors: |
Myers; Robert L. (Loveland,
CO) |
Assignee: |
Hewlett-Packard Development Company
L.P. (Houston, TX)
|
Family
ID: |
27610355 |
Appl.
No.: |
10/062,803 |
Filed: |
January 31, 2002 |
Current U.S.
Class: |
345/502; 345/1.1;
345/519; 710/303 |
Current CPC
Class: |
G06F
1/1632 (20130101); G06F 3/1407 (20130101); G09G
2370/042 (20130101); G09G 2330/021 (20130101); G06F
3/1423 (20130101) |
Current International
Class: |
G06F
1/16 (20060101); G06F 3/14 (20060101); G06F
015/16 () |
Field of
Search: |
;345/1.1,2.1,3.1,501-503,519,520,1.2 ;710/300,303,304 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tung; Kee M.
Claims
What is claimed is:
1. A portable computer system, comprising a portable computer unit
having: a portable computer unit interface configured to connect
the portable computer unit to a docking station and to receive
video control signals from the docking station; a processor; a
video display; and a graphics controller coupled between the
processor, the video display, and the docking station interface and
configured to convert video output signals received from the
processor into locally-generated video control signals,
automatically determine performance the video control signals
received from the portable computer interface provide relative to
the locally-generated video control signals, and selectively
transmit to the video display either the locally-generated video
control signals or the video control signals received from the
portable computer unit interface based on the automatic relative
performance determination.
2. The portable computer system of claim 1, wherein the graphics
controller is responsive to an active connection status signal
indicative of a connection between the portable computer unit and
an external source of video control signals.
3. The portable computer system of claim 2, wherein the graphics
controller is configured to generate an active connection status
signal based upon one or more signals received from the portable
computer unit interface.
4. The portable computer system of claim 3, wherein the graphics
controller is configured to transmit an active connection status
signal to the processor.
5. The portable computer system of claim 2, wherein the processor
is programmed to generate an active connection status signal based
upon one or more signals received from the portable computer unit
interface.
6. The portable computer system of claim 2, wherein the graphics
controller is configured to switch from transmission of
locally-generated video control signals to transmission of video
control signals received from the portable computer unit interface
in response to an active connection status signal.
7. The portable computer system of claim 1, wherein the portable
computer unit further comprises a display controller coupled
between the graphics controller and the video display and
configured to drive the video display based upon video control
signals received from the graphics controller.
8. The portable computer system of claim 1, wherein the portable
computer unit further comprises one or more external display ports
configured to connect the portable computer unit to one or more
respective external video displays.
9. The portable computer system of claim 8, wherein the graphics
controller is operable to selectively transmit video control
signals to one or more of the video display and the one or more
external display ports.
10. The portable computer system of claim 1, wherein the graphics
controller is operable to selectively transmit video display
identification signals to one of a local display adapter and the
portable computer unit interface.
11. The portable computer system of claim 10, wherein the graphics
controller is configured to switch from transmission of video
display identification signals to the local display adapter to
transmission of video display identification signals to the
portable computer unit interface in response to an active
connection status signal.
12. The portable computer system of claim 1, wherein the graphics
controller comprises a multiplexer.
13. The portable computer system of claim 1, wherein the graphics
controller is implemented as a monolithic integrated device.
14. The portable computer system of claim 1, further comprising a
docking station having an interface configured to connect to the
portable computer unit through the portable computer unit
interface.
15. The portable computer system of claim 14, wherein the docking
station comprises a display adapter operable to convert into video
control signals video output signals received from the processor of
the portable computer unit.
16. The portable computer system of claim 1, wherein the graphics
controller selectively transmits the video control signals received
from the portable computer unit interface to the video display in
response to a determination that the video control signals received
from the portable computer unit interface provide higher
performance than the locally-generated video control signals.
17. The portable computer system of claim 1, wherein the graphics
controller selectively transmits the locally-generated video
control signals to the video display in response to a determination
that the video control signals received from the portable computer
unit interface fail to provide higher performance than the
locally-generated video control signals.
Description
TECHNICAL FIELD
This invention relates to systems and methods of switching between
internal and external display adapters in a portable computer
system.
BACKGROUND
A portable computer system typically includes a self-contained
portable computer unit that includes a processor, memory and a
video display, and typically operates under battery power. As used
herein, the term "portable computer unit" broadly refers to any
computer system that is small enough to be carried easily by a
user. The portable computer unit may be called by any number of
names, including a laptop computer, a notebook computer, a
sub-notebook computer, a hand-held computer, a palmtop computer, a
pocket computer, and a notepad computer. The portable computer
system also typically includes a docking station to which the
portable computer unit may connect in order to access various
services and functionality usually only available to desktop
computer systems, including access to network adapters and
peripheral devices, such as printers, scanners and large external
monitors. The portable computer unit typically connects to the
docking station through mating socket-type connections.
The portable computer unit typically includes a display adapter. As
used herein the term "display adapter" refers broadly to a hardware
device that converts images created in a computer to the electronic
signals required by a display device. Other terms that have been
used to refer to a display adapter include graphics adapter,
graphics board, graphics card, graphics controller, video display
adapter, video display board, video display card, video display
controller, video adapter, video board, video card, video
controller, display board, display card, display controller, VGA
adapter, VGA board, VGA card and VGA controller. When the portable
computer unit is "undocked" (i.e., not connected to the docking
station), the video adapter may be used to control the display of
graphics on the local video display of the portable computer unit.
When the portable computer unit is "docked" (i.e., connected to the
docking station), the video adapter may be used to control the
display of graphics on an external monitor that is connected to the
docking station.
SUMMARY
The invention features a scheme (systems and methods) for switching
between internal and external display adapters in a portable
computer system. The invention enables a portable computer unit to
drive its video display with a local adapter that is optimized for
mobile usage (e.g., enhanced power management) when undocked and to
drive its video display with a higher performance external display
adapter, which typically is not constrained by power management
considerations, when docked. In this way, the invention enables the
portable computer unit to access higher performance graphics
hardware devices that commonly are available only to desktop
computer systems.
In one aspect, the invention features a portable computer system
that includes a portable computer unit that has a portable computer
unit interface, a processor, a video display, and a graphics
controller. The portable computer unit interface is configured to
connect the portable computer unit to a docking station and to
receive video control signals from the docking station. The
graphics controller is coupled between the processor, the video
display, and the docking station interface. The graphics controller
is configured to convert video output signals that are received
from the processor into locally-generated video control signals,
and to selectively transmit to the video display locally-generated
video control signals or video control signals that are received
from the portable computer unit interface.
Embodiments in accordance with this aspect of the invention may
include one or more of the following features.
The switch preferably is responsive to an active connection status
signal indicative of a connection between the portable computer
unit and an external source of video control signals. In some
embodiments, the graphics controller is configured to generate an
active connection status signal based upon one or more signals
received from the portable computer unit interface. The graphics
controller may be configured to transmit an active connection
status signal to the processor. In other embodiments, the processor
is programmed to generate an active connection status signal based
upon one or more signals received from the portable computer unit
interface. The switch may be configured to switch from transmission
of locally-generated video control signals to transmission of video
control signals that are received from the portable computer unit
interface in response to an active connection status signal.
The portable computer unit may include a display controller (or
driver) that is coupled between the graphics controller and the
video display and is configured to drive the video display based
upon video control signals received from the graphics
controller.
The portable computer unit also may include one or more external
display ports that are configured to connect the portable computer
unit to one or more respective external video displays. The
graphics controller may be operable to selectively transmit video
control signals to one or more of the video display and the one or
more external display ports.
The graphics controller preferably is operable to selectively
transmit video display identification signals to one of a local
display adapter and the portable computer unit interface. The
graphics controller may be configured to switch from transmission
of video display identification signals to the local display
adapter to transmission of video display identification signals to
the portable computer unit interface in response to an active
connection status signal.
The graphics controller may comprise a multiplexer. In some
embodiments, the graphics controller is implemented as a monolithic
integrated device.
The portable computer system may include a docking station having
an interface that is configured to connect to the portable computer
unit through the portable computer unit interface. The docking
station preferably comprises a video adapter that is operable to
convert into video control signals video output signals that are
received from the processor of the portable computer unit.
In another aspect, the invention features a portable computer
method in accordance with which video control signals, which are
received from one of a local display adapter of the portable
computer unit and an external display adapter of a docking station,
are selectively transmitted to a video display of a portable
computer unit.
Embodiments in accordance with this aspect of the invention may
include one or more of the following features.
The portable computer method may include the step of determining
whether the portable computer unit is connected to a source of
video control signals that is external to the portable computer
unit. Video control signals that are received from the local
display adapter may be transmitted to the video display in response
to a determination that the portable computer unit is unconnected
to the external source of video control signals. Video control
signals that are received from the external display adapter may be
transmitted to the video display in response to a determination
that the portable computer unit is connected to the external source
of video control signals.
The portable computer method also may include the step of
selectively transmitting video control signals to one of the
portable computer unit video display and an external video display
that is connected to the docking station.
Other features and advantages of the invention will become apparent
from the following description, including the drawings and the
claims.
DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram of a portable computer system, including
a portable computer unit and a docking station.
FIG. 2 is a block diagram of certain graphics hardware and graphics
software components of the portable computer system of FIG. 1.
FIG. 3 is a flow diagram of a method of switching between internal
and external display adapters in a portable computer system.
FIG. 4 is a block diagram of signals flowing through certain
components of the portable computer unit illustrated in FIG. 1.
DETAILED DESCRIPTION
In the following description, like reference numbers are used to
identify like elements. Furthermore, the drawings are intended to
illustrate major features of exemplary embodiments in a
diagrammatic manner. The drawings are not intended to depict every
feature of actual embodiments nor relative dimensions of the
depicted elements, and are not drawn to scale.
Referring to FIG. 1, in one embodiment, a portable computer system
10 includes a portable computer unit 12 and a docking station
14.
Portable computer unit 12 may be implemented in the form of any one
of a wide variety of conventional computer systems that are small
enough to be carried by a user, including a laptop computer, a
notebook computer, a sub-notebook computer, a hand-held computer, a
palmtop computer, a pocket computer, and a notepad computer. In
general, portable computer unit 12 includes an interface 16, a
processing unit 18, a video display 20, and a graphics controller
22. Interface 16 is configured to connect portable computer unit 12
to docking station 14 and to exchange with docking station 14
conventional docking station signals 24 as well as video control
signals 26 for driving video display 20. Processing unit 18 may
include one or more processors, each of which may be in is the form
of any one of various commercially available processors. Video
display 20 may be a conventional flat panel display, such as a LCD
(liquid crystal display), a plasma display, an EL display
(electro-luminescent display) and a FED (field emission display).
Portable computer unit 12 also may include other components (not
shown), such as a system memory and a system bus. The system memory
typically includes a read only memory (ROM) that stores a basic
input/output system (BIOS) that contains start-up routines for
portable computer unit 12, and a random access memory (RAM). The
system bus may be a memory bus, a peripheral bus or a local bus,
and may be compatible with any of a variety of bus protocols,
including PCI, VESA, Microchannel, ISA, and EISA. Portable computer
unit 12 also may include a hard drive, a floppy drive, and CD ROM
drive that are connected to the system bus by respective
interfaces. The hard drive, floppy drive, and CD ROM drive contain
respective computer-readable media disks that provide non-volatile
or persistent storage for data, data structures and
computer-executable instructions. Other computer-readable storage
devices (e.g., magnetic tape drives, flash memory devices, and
digital video disks) also may be used with portable computer unit
12. A user may interact (e.g., enter commands or data) with
portable computer unit 12 using a keyboard and a mouse. Other input
devices (e.g., a microphone, joystick, or touch pad) also may be
provided.
As explained in detail below, graphics controller 22 is configured
to convert video output signals received from processing unit 18
into locally-generated video control signals and to selectively
transmit to the video display the video control signals that are
generated locally or video control signals that are received from
interface 16. In this way, when undocked, portable computer unit 12
may drive video display 20 with a local adapter that is optimized
for mobile usage (e.g., enhanced power management) and, when
docked, portable computer unit 12 may drive video display 20 with a
higher performance external display adapter, which typically is not
constrained by power management considerations.
Docking station 14 may be implemented in a form that is designed to
complement and enhance the functionality of portable computer unit
12. In general, docking station 12 includes an interface 28, a
display adapter 30, and one or more other devices 32, which may be
in the form of any of a wide variety of different conventional
docking station devices, including storage disk drives, network
adapters, and other peripheral adapters. Interface 28 is configured
to connect to portable computer unit 12 through portable unit
interface 16. The interface connection may be ISA-based or
PCI-based, or both. Interface 28 is configured to exchange with
portable computer unit interface 16 conventional docking station
signals 24 as well as video control signals 26 for driving video
display 20. Display adapter 30 and the other docking station
devices 32 communicate with interface 28 over a system bus 33. In
some embodiments, docking station 12 may have an internal power
supply (not shown) that is configured to power all of the component
devices of docking station 12. In other embodiments, docking
station 12 may not have an internal power supply, in which case
portable computer unit 12 would be configured provide power to
docking station 12 through a switch.
Referring to FIG. 2, in one embodiment, portable computer unit 12
includes a display control architecture 40 that includes a graphics
hardware component 42 and a graphics software component 44.
Graphics controller 22 includes an internal (or local) display
adapter 46 that is configured to convert video output signals that
are received from processing unit 18 into video control signals.
Graphics controller 22 also includes a video data switch 48 that is
configured to selectively transmit to video display 20 video
control signals that are generated locally by local display adapter
46 or external video control signals that are received from
external display adapter 30 through interface 16. In operation, one
or more software application programs 50 may generate data 52
(e.g., text, windows and other graphical objects, and command
structures, such as menus and dialog boxes) that is to be displayed
on video display 20. An operating system 54 converts the
application program data 52 into video output signals. Operating
system 54 includes a display manager 56 that communicates with
graphics controller 22 through a video driver 58. When docked,
display manager 56 communicates with external display adapter 30
through a video driver 60. Display manager 56 also communicates
with other parts of operating system 54 and with application
programs 50 to coordinate these components with the current display
environment.
Referring to FIG. 3, in one embodiment, graphics controller 22 is
configured to automatically switch the source of video control
signals from the internal, local display adapter 46 to the external
display adapter 30 that is located on docking station 14, as
follows.
Graphics controller 22 determines whether portable computer unit 12
is connected to an external source of video control signals (step
70). As shown in FIG. 4, graphics controller 22 may include control
logic 72 that is coupled to receive one or more video control
signals 26 from interface 16. Video control signals 26 may include
standard RGB video data signals 74 and one or more other video
control signals 76 (e.g., external display clock signals and
synchronization signals, such as line and frame synchronization
signals and horizontal and vertical synchronization signals). Based
upon video control signals 76, control logic 72 is configured to
generate a connection status signal 78 (EXT_HW_ON) that indicates
whether portable computer unit 12 is connected to an external
source of video control signals. For example, in one embodiment,
control logic 72 may set the connection status signal 78 to
"active" if one of the following conditions is satisfied: an
external horizontal synchronization signal with a frequency greater
than 10 kHz is detected; an external vertical synchronization
signal with a frequency greater than 10 kHz is detected; or an
external pixel clock signal with a frequency greater than 1 MHz is
detected. The connection status signal 78 is transmitted to
processing unit 18 so that the system can accommodate the video
source that is currently driving video display 20. If control logic
72 does not detect a connection to an external source of video
control signals (step 70), the connection status signal 78 is set
to "inactive," which sets a switch 80 (e.g., a 2:1 multiplexer) to
transmit to video display 20 video control signals 82 that are
generated by internal display adapter 46 (step 84). Video control
signals 82 may include standard RGB video data signals 86 and other
video control signals 88 (e.g., synchronization signals, clock
display signals, and display enable signals). In some embodiments,
if control logic 72 detects a connection to an external source of
video control signals (step 70), control logic 72 may determine
whether the external source of video control signals performs
better than internal display adapter 46 (step 90). In these
embodiments, if the external source of video control signals
provides superior performance (step 90), control logic 72 sets the
connection status signal 78 to "active," which sets switch 80 to
transmit to video display 20 video control signals 82 that are
received from the external source of video control signals (step
92). If the external source of video control signals does not
provide superior performance (step 90), the connection status
signal 78 is set to "inactive," which sets a switch 80 (e.g., a 2:1
multiplexer) to transmit to video display 20 video control signals
82 that are generated by internal display adapter 46 (step 84). In
other embodiments, control logic 72 does not determine whether the
external source of video control signals provides superior
performance and, instead, simply sets the connection status signal
78 to "active" whenever a connection to an external source of video
control signals is detected (step 92).
As shown in FIG. 4, in some embodiments, graphics controller 22 may
include an external display connector (or port) 94 that is
configured to connect portable computer unit 12 to an external
video display. In these embodiments, portable computer unit 12 may
include an interface 96 (e.g., a TMDS transmitter, a LVDS
transmitter, or a digital-to-analog converter) that is configured
to perform digital-to-analog conversion or digital output functions
as may be provided to drive an external video display. Because the
video control signal switching function is implemented by switch 80
in the digital data path prior to the internal display panel
connection and prior to the external display interface 96, an
external display may be selectively driven by either the internal
display adapter 46 or the external display adapter 30 (when
portable computer unit is docked).
In some embodiments, graphics controller 22 also may include a
switch 98 (e.g., a 2:1 multiplexer) that is configured to route to
the graphics hardware that currently is in use any video display
identification signals that may be received from display 20 or the
external display connector 94. In this way, the system will always
have access to the display identification information via the
current graphics subsystem.
Other embodiments are within the scope of the claims.
Although systems and methods have been described herein in the
context of a particular computing environment, these systems and
methods are not limited to any particular hardware or software
configuration, but rather they may be implemented in any portable
computing or processing environment, including in digital
electronic circuitry or in computer hardware, firmware or
software.
In addition, in the embodiments described above, graphics
controller 22 has been shown as a separate component that may be
located on a separate monolithic card or printed circuit board. In
other embodiments, however, graphics controller 22 may be
incorporated with other components on a single card, such as a
motherboard for portable computer unit 12.
In some embodiments, the video control signal switching function
may be performed under direct control of processing unit 18, rather
than through the use of switch 80 of graphics controller 22. In
addition, in some embodiments, processing unit 18 may perform the
switching control function, with an automatic override based upon
connectivity status such that the internal display connection would
always be made in the event of an unexpected disconnection or
failure of the external graphics hardware.
Still other embodiments are within the scope of the claims.
* * * * *